The present invention relates to a method for production of a ceramic product, and to a ceramic product. The invention is favorable to musical instruments, building materials, etc., and to a method for producing them.
Heretofore, for example, known is a method of applying a synthetic resin to a machinable ceramic material followed by finishing the resulting, resin-dipped ceramic material into musical instruments having a desired form (Japanese Patent Laid-Open No. 181787/1990).
Compared with other conventional instruments made of wood, the instruments produced according to the method have the advantage of good durability intrinsic to the ceramic material and the synthetic resin constituting them and have good sound characteristics necessary to musical instruments not absorbing water and impervious to air. In addition, not using natural wood, the method for production is favorable for the protection of the environment.
Naturally, however, the ceramic product to be produced must have various characteristics necessary for their applications. Nevertheless, in the conventional method for production of a ceramic product mentioned above, musical instruments are merely produced with no consideration given to the necessary characteristics except the durability, the absence of water absorption and the air imperviousness.
Specifically, in the conventional method for production, nothing is taken into consideration relating to the applications of the ceramic product to be produced as to what characteristics are needed by the ceramic product and how the ceramic product is to be constituted so as to have the necessary characteristics. Therefore, in the conventional method for production, the ceramic product produced could have the necessary appearance and function to some degree, but are as yet not clarified as to whether or not they have surely satisfactory characteristics for their applications.
The present invention has been made in consideration of the current situation in the art mentioned above, and its object is to ensure the production of a ceramic product having satisfactory characteristics for predetermined applications.
The method for production of a ceramic product of the invention is characterized in that the desired characteristics of the ceramic product to be produced therein are first grasped, a porous ceramic material having the first characteristic and a fluid having the second characteristic are then prepared, the fluid is at least infiltrated into the ceramic material, and at least one of the first characteristic, the second characteristic and the infiltration ratio are controlled to produce the ceramic product.
In the method for production of the invention, the desired characteristics of the ceramic product to be produced are first grasped in accordance with the use of the ceramic product.
For example, in case where the ceramic product to be produced is a sounding medium for percussion instruments such as xylophones, marimbas, clappers, castanets, percussion blocks (such as those in Buddhist temples), etc., its necessary characteristics will be high density, high hardness and small internal friction (Qxe2x88x921).
In case where the ceramic product to be produced is a sound plate for stringed instruments such as pianos, violins, guitars, biwas (four-stringed Japanese lutes), kotos (Japanese harps), etc., its density will have to be within a specific range, and, in addition, its specific elastic modulus will have to be high and its sound attenuation factor will have to be low.
In case where the ceramic product to be produced is a resonator pipe for woodwinds such as clarinets, recorders (English flutes), shakuhachies (five-holed vertical bamboo flutes), etc., its sound attenuation factor will have to be within a specific range, and its elastic modulus (Young""s modulus) will have to be within a specific range and will have to be anisotropic.
In addition, the instruments mentioned above will have to be further discussed for their other characteristics including vibration characteristics, sound radiation characteristics, vibration transmission characteristics, etc. Moreover, in case where they require machining in producing them, they must have good machinability for their mechanical characteristics. Accordingly, the sound characteristics and the mechanical characteristics of the ceramic product for such instruments are first grasped.
Regarding the vibration characteristics of instruments for percussion sounds, the beaten surface of the instruments will be readily deformed. In case where the instruments are made of a material having a longer contact time with a beating medium applied thereto, they could hardly produce sound components up to the high-frequency level, and their sounds will be mild as consisting essentially of low-frequency components.
The sound radiation characteristics of instruments are definitely reflected by the sounds that are produced by a rod sample of the same material as that of the instruments forcedly vibrated to give a flat frequency vibration sound (white noise). The sounds produced under such forced vibration give a sound spectrum to reflect the sound radiation characteristics of the instruments. The level of the sound pressure from instruments made of a hard material greatly fluctuates at around the resonance point; but that from instruments made of a soft material fluctuates only a little. This is because the internal friction of instruments made of a hard material falls between {fraction (1/10)}, and {fraction (1/30)} of that of instruments made of a soft material. In addition, instruments made of a hard material have a higher sound transmission efficiency (degree of sound transmission) to give vibration sounds up to a high-frequency level, with the increase in their resonance point peak. Accordingly, it is understood that instruments made of a soft material have a filter effect capable of relatively strengthening low-frequency components to thereby depress high-frequency components that are offensive to human ears. In case where a ceramic material of uniform crystal orientation is used in producing instruments and where the internal friction of the material to be caused by the strain deformation thereof in the crystal orientation direction in the instruments is enlarged for high-frequency components, the filter effect of the instruments will be remarkable under free sound attenuation condition, and will characterize the mildness of the sounds produced by the instruments. The difference between the internal friction to be caused by bending strain and that to be caused by shearing strain will also give a sound spectrum.
Vibration will be more readily transmitted from a material having a smaller intrinsic sound resistance (sound impedance) (Excfx81)xc2xd, and a material having a larger specific Young""s modulus (elastic modulus/specific gravity) ensures higher sound transmission and higher vibration response. Instruments made of a soft material have a low density and a low elastic modulus, and their sound resistance is low. However, in case where the soft material for instruments is a ceramic material of uniform crystal orientation, the specific Young""s modulus in the crystal orientation direction of the instruments will be on the same level as that of instruments made of a hard material. Accordingly, the instruments made of such a soft ceramic material will be readily vibrated and their response to vibration change is good. The internal friction of instruments made of a soft material is large relative to the specific Young""s modulus thereof. Therefore, the frequency characteristics of instruments made of a soft material are flat, compared with those of instruments made of a hard material. Accordingly, instruments made of a soft material are characterized in that each sound produced by them is rapidly attenuated and does not overlap with any others, and they will be therefore suitable to sound plates.
More concretely, in case where the ceramic product to be produced is for a mouthpiece body of a clarinet integrated with a resonator plate for a reed made of reed (plant), it must have sound characteristics including elastic modulus, internal friction, etc., and must have mechanical characteristics including machinability, etc. Therefore, for such a mouthpiece body, the sound characteristics and mechanical characteristics of the ceramic product to be produced are first grasped.
In case where the ceramic product to be produced is for building materials or for constitutive members for machines, etc., such building materials and constitutive members must have mechanical characteristics including tensile strength, bending strength, elastic modulus, machinability, etc. Therefore, for such building materials and constitutive members, the mechanical characteristics of the ceramic product to be produced are first grasped.
With that, a ceramic material and a fluid are prepared. The ceramic material is porous, and its first characteristic must be grasped. For the ceramic material, for example, employable is a machinable, sintered ceramic substance described in Japanese Patent Publication No. 21632/1992. The first characteristic of the ceramic material includes, for example, the apparent porosity, the mean pore radius and the machinability thereof. On the other hand, liquid and gaseous materials can be used for the fluid. The liquid material includes resin and rubber. The resin may be any of thermosetting resins or thermoplastic resins. In case where the fluid is a thermosetting resin selected from acrylic resins, unsaturated polyesters, epoxy resins, ABS, etc., its second characteristic is, for example, the elastic modulus of the thermosetting resin.
Next, the fluid is at least infiltrated into the ceramic material, and at least one of the first characteristic, the second characteristic and the infiltration ratio is controlled to produce the intended ceramic product. In case where the infiltration ratio is controlled, pores filled with air can be left in the ceramic product produced. In that case, therefore, the ceramic product produced shall have a composite structure composed of the ceramic material, the liquid such as a thermosetting resin or the solid from it, and air, and can realize the desired characteristics in a more preferred manner. In case where a thermosetting resin is used, it is infiltrated into the ceramic material and then cured therein to give a ceramic product. For the infiltration method to be employed herein, the parameters including the degree of reduced pressure or increased pressure, the processing time and the processing temperature may be suitably determined.
The ceramic product thus obtained is composed of the porous ceramic material having the first characteristic and the fluid having the second characteristic and having been infiltrated into the ceramic material or the solid from the fluid, and has the desired third characteristic attained by controlling at least one of the first characteristic, the second characteristic and the infiltration ratio. After the process, the ceramic product may be optionally post-processed for surface treatment including painting and polishing for further improving or modifying its design, quality, safety and feel.